... That is not entirely true (not to say it is false, but more nuanced). Much of the court system is elected (or directly appointed by someone elected), which is supposed to balance abuse in the long run. Obviously it takes publicity and a lot of wrangling to make an impact through elections, but it is technically feasible.
I don't find that a satisfactory answer. And I don't think that's "holding them responsible". Let's look at what happens in real life:
One judge said Connick's office had in fact committed a pattern of violations, failing to disclose exculpatory blood type evidence, failing to disclose audio tapes of witness testimony, failing to disclose a deathbed confession of evidence destruction by the prosecuting attorney Gerry Deegan, and failing to disclose eyewitness identification of the killer that did not match Thompson,
And what happened to the people who broke the law and put innocent people in jail?
I'll let you guess.